uh, what exactly are you looking for? can you be more specific? this might help though... TASHowTo - TASVideos
It is generally pretty hard to TAS PC games, there are almost no tools that actually work. There was Hourglass (which was discontinued at some point) and there is libTAS, not sure if there is anything else. Generally you don't just have an easy tool to TAS PC games (especially more modern games) like you can do with emulators for consoles.
I think Celeste for example has their own custom TAS-tools but they might be based on libTAS.
Try your luck with Hourglass if it's Windows, though I doubt it will work. If it's Linux, try libTAS.
For me, when it comes to EMU, they're okay as you don't use tool-assist.
Bizhawk and TAS studio on of my favourite. FCEUX is fast in speed but bizhawl is multi system emulator so thats my choice will be bizhawk
You're asking how to TAS PC on a speedrunning forum? Is helping you not encouraging cheating? You did say TAS and would still be relevant for game research so I'll answer.
The earliest TASes played the games slowed down on emulators. There's a how to TAS video that states as much. Can take that idea and hack the PC games to run slow then speed them back up in editing. Karl Jobst has popular videos for speedrun cheating in Doom, Trackmania and Guitar Hero/Clone Hero, where runners were caught playing in slow motion. He says Cheat Engine can be easily used to slow down games. Sorry I never used it but maybe you can ask on a TAS forum for game-specific help.
I see Hourglass is meant for Windows XP with 32-bit games and does not support mouse input. Every game released today is 64-bit. Not sure if it will run under a Windows XP virtual machine but the OS can be uhh found online and mid-2000s laptops running genuine XP are cheap and plentiful on eBay.